Robust, reliable, and quantitative detection of biomarkers at ultra-low concentration is of great importance in clinical settings. Biosensor, an analytical device used for sensitive and selective ...detection of biomarkers offers various advantages over the conventional clinical diagnosis, which is both time consuming and not suitable for point of care/onsite diagnosis. A revolution in the understanding and synthesis of nanomaterials in the last couple of decades contributed significantly to the development of the biosensors in terms of sensitivity, catalytic activity, biocompatibility, and robustness. Additionally, nanomaterials help in miniaturization of the sensing platform and helping in the commercial success of portable biosensor kits. Surface engineering equally contributed to the biosensor development by ensuring a reproducible and stable sensing surface, efficient analyte-biorecognition element interaction, and reduced fouling effect in biological solution. Due to nanomaterial integration and surface engineering, biosensors are now equally sensitive to the lab-based sophisticated instruments to detect a wide range of molecules of clinical significance. In this review, various types of biosensors, their designs, and their working principles have been discussed. A detailed account of various types of nanomaterials, their functionalization and characterization have also been discussed. The analytical performances of biosensors for both clinical validation and analyte detection have been incorporated here. The recent trends in advanced biosensors, such as smartphone interface for biosensing, nanozymes, lab-on-a-chip based detection methods have been discussed.
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•Governing adsorption mechanisms of heavy metals onto carbon adsorbents are summarized.•Various methods for introduction of oxygen, nitrogen, and sulfur functional groups onto carbon ...surfaces are categorized.•Effects of various functional groups on heavy metal adsorption onto different carbon materials are discussed.•Perspectives of future work on functionalized carbon adsorbents for heavy metal removal is also presented.
Carbon-based adsorbents such as graphene and its derivatives, carbon nanotubes, activated carbon, and biochar are often used to remove heavy metals from aqueous solutions. One of the important aspects of effective carbon adsorbents for heavy metals is their tunable surface functional groups. To promote the applications of functionalized carbon adsorbents in heavy metal removal, a systematic documentation of their syntheses and interactions with metals in aqueous solution is crucial. This work provides a comprehensive review of recent research on various carbon adsorbents in terms of their surface functional groups and the associated removal behaviors and performances to heavy metals in aqueous solutions. The governing removal mechanisms of carbon adsorbents to aqueous heavy metals are first outlined with a special focus on the roles of surface functional groups. It then summarizes and categorizes various synthesis methods that are commonly used to introduce heteroatoms, primarily oxygen, nitrogen, and sulfur, onto carbon surfaces for enhanced surface functionalities and sorptive properties to heavy metals in aqueous solutions. After that, the effects of various functional groups on adsorption behaviors of heavy metals onto the functionalized carbon adsorbents are elucidated. A perspective of future work on functional carbon adsorbents for heavy metal removal as well as other potential applications is also presented at the end.
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Polyphenols, the ubiquitous secondary metabolites of plants, are an important part of human diet and are essential for plant functions. They have attracted considerable interest due ...to their important biological activities as well as intriguing chemical and physical properties. Polyphenols allow a whole panoply of chemical and physical interactions with interesting molecules and surfaces to be established. Thus, polyphenols can serve as versatile building blocks for the preparation of various functional materials, such as capsules, antibacterial and antioxidant films, micro/nanoparticles, membranes, electronic and energy storage materials, hydrogels, and cell encapsulants, with fascinating structures and properties. In addition to their important roles in engineering of functional materials, they also emerge as pivotal components in the construction of versatile surfaces, including antifouling, antibacterial, antioxidant, cell adherent and proliferable, enzyme-immobilized, patternable and peptide-embedded surfaces. This review will describe the main interactions/reactions involving polyphenols for the design of functional materials and the construction of versatile surfaces. This review will also illustrate and discuss current applications of polyphenols in material and surface sciences.
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•Novel graphene-chitosan-silver composite for lead sensing.•Self-reduction of Ag2+ and anchoring of silver nanoparticles on the surface of GO-CS.•Surface silver nanoparticles offer ...selective lead sensing with superior sensitivity.•The developed sensor used for detection of lead in contaminated water.
Owing to the adverse effect of lead (Pb) on almost every organ of the body and predominantly, the nervous system, a sensitive and selective detection of the lead below the permissible limit is highly desirable. In the present work, an electrochemical lead sensor based on graphene oxide-chitosan (GO-CS) biocomposite, surface functionalized with silver nanoparticles has been demonstrated. The GO-CS biocomposite formation is ascribed to the hydrogen bonding and electrostatic interaction between the oxygen-containing functional groups of GO and chitosan. The amide and carboxyl groups present in GO-CS helps in the reduction of Ag2+ and anchoring of the silver nanoparticles (Ag0) on the surface. This eventually resulted in the enhanced electrochemical activity and charge transfer thereby facilitating selective chemisorption of Pb(II) on GO-CS-Ag. The sensor exhibited superior response with limit of detection (LOD) of 0.15 ppb and a linear detection range from 0.2 to 40 ppb (MRL = 10 ppb). Importantly, the sensor is highly selective towards Pb(II) with selectivity factor ranging from 5 to 8, as compared with other heavy metal ions. The developed sensor has been tested and validated for lead detection in contaminated water samples wherein the results were found to be in agreement with those from atomic absorption spectroscopy (AAS) analysis.
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•Functionalized cellulose nanocrystals (CNCs) for dye absorption.•Selective binding of methylene blue by polydopamine-CNC.•ITC analysis confirmed the types of binding interactions.
In ...this study, cellulose nanocrystals (CNCs) were evaluated as potential adsorbents for the selective adsorption and separation of organic dyes mixtures (methylene blue (MB), with either methyl orange (MO) or rhodamine b (RB) or crystal violet (CV)). The role of surface functional groups on the dye-CNC interaction was examined using pristine and surface-functionalized CNCs, such polydopamine (PD) and melamine–formaldehyde (MF) coated CNCs (PD-CNCs and MF-CNCs respectively). Batch adsorption studies on MB/MO dye mixture showed that pristine CNCs bearing anionic sulfate ester groups exhibited preferential adsorption for MB, with a 85.78% adsorption efficiency. This preferential adsorption was further enhanced in the case of PD-CNCs, which showed 100% adsorption efficiency for MB. Additional studies on MB/RB and MB/CV dye mixtures confirmed that the improved selectivity of PD-CNCs towards MB is associated with the synergistic binding interactions, such as electrostatic attraction, π-π stacking, and hydrogen bonding. MF-CNCs with cationic amine groups displayed selective binding towards MO, an anionic dye. Also, PD-CNCs and MF-CNCs were found to completely separate MB and MO from a diluted MB/MO dye mixture. Isothermal titration calorimetry and dye flocculation experiments confirmed that the selective binding is associated with the surface-functionality of CNCs.
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•Performance of a functionalization strategy fosters strategy of materials improve.•Applications of modified inorganic NPs are suited for biomedicine and technology.•Superior ...characteristics of hybrid coatings improve materials multimodal properties.
This review presents the latest innovations and trends in the field of surface functionalization of various nanomaterials. The most recent protocols of smart materials fabrication as well as the main challenges which should be overcome in order to improve their final performance are discussed here. Particular attention has been paid to the properties improvement of polymer, silica, inorganic and hybrid nanomaterials and their potential for application in many fields, from industry, materials science, environmental protection to advanced biomedicine.
•Synthesis methods of ordered mesoporous carbons (OMC) are summarized.•Adsorptive removal of contaminants by OMC is systematically documented.•Effects of various modifications of OMCs on pollutant ...removal are reviewed.•Recent advances and future directions on OMC applications are highlighted.
An ideal adsorbent should possess the ability of being easily fabricated, cheap to produce, and have a high adsorptive capacity for adsorbates. Ordered mesoporous carbon (OMC), a moderately new member of the carbonaceous family of adsorbents, has arisen as a potential adsorbent because of its distinct features such as high BET surface area, large pore size and porosity volume, tunable surface chemistry and thermo-mechanical stability. In this review paper, we have presented a systematic documentation of all the research efforts on OMC preparation, modification, characterization, and environmental application for pollutant removal. The subsequent characterizations of OMC employing different techniques, such as, N2 Adsorption-Desorption Isotherm, scanning electron microscope (SEM) and transmission electron microscope (TEM) images, X-ray diffraction (XRD) pattern, fourier transform infrared spectroscopy (FTIR) and X-ray photon spectroscopy (XPS) spectra, are summarized. Furthermore, we have compared the adsorption performance of different modified OMCs towards different inorganic pollutants, such as heavy metals, and various organic pollutants categorically, such as dyes, phenols and their derivatives, volatile organic compounds (VOCs), alkaloids, nitrogen containing organic compounds, and vitamins. Future research directions on functionalized OMC for the adsorptive removal of emerging pollutants and other environmental applications are also provided.
Cellulose nanocrystals (CNCs) have attracted great interest from researchers from academic and industrial areas because of their interesting structural features and unique physicochemical properties, ...such as magnificent mechanical strength, high surface area, and many hydroxyl groups for chemical modification, low density, and biodegradability. CNCs are an outstanding contender for applications in assorted fields comprehensive of, e.g., biomedical, electronic gadgets, water purifications, nanocomposites, membranes. Additionally, a persistent progression is going on in the extraction and surface modification of cellulose nanocrystals to fulfill the expanding need of producers to fabricate cellulose nanocrystals-based materials. In this review, the foundation of nanocellulose that emerged from lignocellulosic biomass and recent development in extraction/preparation of cellulose nanocrystals and different types of cellulose nanocrystal surface modification techniques are summed up. The different sorts of cellulose modification reactions that have been discussed are acetylation, oxidations, esterifications, etherifications, ion-pair formation, hydrogen bonding, silanization, nucleophilic substitution reactions, and so forth. The mechanisms of surface functionalization reactions are also introduced and considered concerning the impact on the reactions. Moreover, the primary association of cellulose and different forms of nanocellulose has likewise been examined for beginners in this field.
The upcycling of discarded garments can help to mitigate the environmental impact of the textile industry. Here, we fabricated hybrid anisotropic foams having cellulose nanocrystals (CNCs), which ...were isolated from discarded cotton textiles and had varied surface chemistries as structural components, in combination with xanthan gum (XG) as a physical crosslinker of the dispersion used for foam preparation. All CNCs had crystallinity indices above 85 %, zeta potential values below −40 mV at 1 mM NaCl, and true densities ranging from 1.61 to 1.67 g·cm−3. Quartz crystal microbalance with dissipation (QCM-D) measurements indicated weak interactions between CNC and XG, while rheology measurements showed that highly charged CNCs caused the XG chains to change from an extended to a helicoidal conformation, resulting in changes the in viscoelastic properties of the dispersions.
The inclusion of XG significantly enhanced the compression mechanical properties of the freeze-casted foams without compromising their thermal properties, anisotropy, or degree of alignment. CNC-XG foams maintained structural integrity even after exposure to high humidity (91 %) and temperatures (100 °C) and displayed very low radial thermal conductivities. This research provides a viable avenue for upcycling cotton-based clothing waste into high-performance materials.
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•CNCs with diverse surface chemistries were extracted from discarded cotton fabrics and used to prepare anisotropic foams•The addition of xanthan gum enhanced the gel strength of the foam precursor, leading to improved foam mechanical properties•QCM-D measurements indicated minimal interactions between XG and CNCs, likely due to electrostatic repulsions•Foams prepared from CNC and CNC-XG dispersions exhibited minimal shrinkage, high alignment, and low thermal conductivity.
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